I'm interested in urban planning and mass transit. As OSM matures further I'm hoping it will be a useful source of data for research. There aren't enough open data sets out there that people who aren't professionals have access to, especially in useful formats. I think OSM has the potential to change that.
One particular thing I would like to do is make maps of the San Francisco transit system. I think better ones could be made but at the moment all the data is locked up. To that end I've been concentrating a lot of my mapping activities on bus stops and bus routes.
I've also been working on making our map more routeable by trying to collect San Francisco Turn Restrictions data and by working on the San Francisco Address Import.
I've tried to make the San Francisco page of the wiki a tool we can use to collaborate.
My mapping technique of choice is hand drawn maps. I walk down a street and mark all points of interest and their relation to the nearest cross streets and any other information. I then use JOSM to mark and tag all the points I've written down. I've used a GPS in the past and for this type of mapping it doesn't actually make things any easier because I still have to write down so much information. In addition to that in parts of the city with lots of tall buildings the GPS is less accurate. I also use walking papers some as well.
So thats me with respect to OSM. If you're in the San Francisco area and want to get together to map or grab a beer and talk mapping drop me a line or else check out our Bay Area OpenStreetMappers meetup.com page to see whats happening next.